Charge-Discharge Behavior of Graphite in Propylene Carbonate-Containing Electrolytes 2011-39-7236
The electrochemical intercalation of lithium-ion into natural
graphite cannot take place in propylene carbonate (PC)-based
electrolytes. Continuous decomposition of PC, accompanied by the
exfoliation of graphite, is observed instead of the intercalation
of lithium-ion. One of the plausible hypotheses to explain this
behavior is that PC-solvated lithium-ion intercalates into graphite
during the first charge, resulting in the exfoliation of graphite.
Therefore, we consider that the solvation structure of lithium-ion
in PC-based electrolytes should strongly influence the
charge-discharge behavior of natural graphite.
We studied the charge-discharge properties of natural graphite
in binary electrolytes consisting of PC and dimethyl carbonate
(DMC) with various mixing ratios. The average solvation numbers of
PC molecules per lithium-ion
(NPC,ave) in PC:DMC binary
electrolytes were evaluated with Raman spectroscopy. We examined
the correlation between the solvation number of PC molecules and
the charge-discharge behavior of natural graphite and discuss the
mechanism of the exfoliation of graphite.